A urine protein creatinine ratio (UP:UC) is used to provide an estimate of the amount of protein lost in the urine, to help evaluate and monitor kidney function, and to help detect and diagnose early kidney damage and disease.
Theoretically speaking, normal individuals usually excrete very small amounts of protein in the urine, however a persistent increased in protein excretion is usually a marker of kidney damage. Quantifying protein in urine is commonly used in the diagnosis of kidney diseases, detection of treatment effects and evaluation of prognosis.
The urine protein test tells the doctor that protein is present in the urine, but it does not indicate which types are present or the cause of the proteinuria.
How is it done?
A urine protein creatinine ratio may be ordered on a random urine sample if a child shows evidence of significant and persistent protein in their urine with the dipstick urine test.
Children, and sometimes adults, occasionally have some degree of transient proteinuria without apparent kidney dysfunction and may have a higher excretion of protein into their urine during the day than at night. The doctor may monitor their urine at intervals to see if the amount of proteinuria changes over time.
Either a 24-hour urine protein or a random protein to creatinine ratio may be used to monitor a person with known kidney disease or damage. A dipstick urine protein and/or a protein to creatinine ratio may be used to screen people on a regular basis when they are taking a medication that may affect their kidney function.
Is it an SOP procedure?
Urine protein to creatinine ratios should only be performed on urine samples with a consideration of the urine specific gravity (a measure of the concentration of solutes in the urine), evidence of excess protein and no evidence of cystitis. There is no point in performing a urine protein-creatinine ratio in a patient with inflammatory conditions in the urinary tract that will increase protein and negate the usefulness of the ratio for determining the source of protein loss.
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